Fix source and binary mismatch errors with aptly publisher
In the case of releases which use reprepro publisher, there was only one published version of a package. This assumption is no longer holds with the aptly publisher and it can have multiple versions of the package in the repository and it is as per design. aptly doesn't remove older versions of a package when a new version is uploaded. Due to this we see errors like Mismatch between APT source and binary.
If there are multiple versions of a binary, check if there is a correspondent source for them, and report error if not.